Japan Suggestions for AVAS sound requirements JASIC

Transcription

1 Japan Suggestions for AVAS sound requirements JASIC 1

2 1. Outline Japan suggestions for the sound requirements for AVAS: 1.At least two bands with adequate sound pressure levels in 1/3 octave band, 2.Audible distance should be proportional to AVAS s overall sound pressure level. Japan conducted verification tests. 2

3 Sound for all Pedestrian For persons with normal hearing, the ear is most sensitive to frequencies between 1 and 5 khz due to the resonance of the ear canal and the transfer function of the ossicles of the middle ear. A 2. Review of Previous Presentation Quoted from Informal document No. GRB (52nd GRB, 6-8 September 2010.) Outstanding band frequency between 1kHz and 5kHz is effective for providing good detectability for pedestrians. Source: ISO Equal Loudness Curves (ISO 226):2003 3

4 Sound for elderly suffering from hearing loss by aging (most of visually impaired people) Elderly persons more than 60 years old have difficulty in detecting sounds higher than 2kHz due to age related hearing loss. More than 70% of visually impaired are over 60 years old. B AVAS needs outstanding band under 1kHz frequency to ensure good detectability for the majority of blind people. Population of Visually Impaired impaired over 60 years old 1.64 million 72% 4.15 million* 73% Visually Impaired includes people with Legal Blindness and Low Vision Japan Data: Brant, M. Yamada et al (2010) Ophthalmic Epidemiology, 17(1), -57 US Data : National Eye Institute (NEI) Prevalence of Blindness Data, *8,000 added to NEI estimate to account for ages <40 years based on Lighthouse International data Impairment (>-20dB) 2kHz 4 Source: Brant, L.J. & Fozard, J.L. (1990). Journal of the Acoustical Society of America

5 Sound for Neighborhood Community Ambient noise measurements taken at different locations in Detroit. - Ambient noise has maximum level in 1kHz band for each traffic condition AVAS frequency bands at the shoulders of the 1 khz band will C allow the lowest sound level possible while maintaining its effectiveness and a quiet environment for neighborhoods 80 Shoulder Shoulder Busy Intersection Starting: OA 77 db Moving: OA 74 db Pa/(m3/s2) db Stopped: OA 65 db Starting: OA 58 db Moving: OA 56 db Neighborhood Near Busy Intersection Stopped: OA 54 db /3 Octave Center Frequency (Hz) 5

6 Japanese Two bands in 1/3 oct. Concept A Outstanding band frequency between 1kHz and 5kHz is effective for providing good detectability for all pedestrians but B. B AVAS needs an outstanding band under 1kHz frequency to ensure good detectability for elderly(suffering from high-frequency hearing loss by aging). C AVAS frequency bands at the shoulders of the 1 khz band will allow the lowest sound level possible while maintaining its effectiveness and a quiet environment for neighborhoods B A ICE Sound power specter AVAS C 0.63kHz 1.0 khz 2.5 khz Frequency 6 1/3 Octave Center Frequency (Hz)

7 3. Indoor Hearing Test Participants : Non-handicapped people and a person who have the same type of hearing loss as the elderly. Test sounds: only 2 bands in 1/3 octave band (adjust to the same band level) Mixed with ambient noise referred by NHTSA in NPRM Present to participants PC1 [2band sound] PC2 [Ambient noise] USB audio interface USBaudio interface Mixer AMP Participant 1 Participant 2 Participant 2 Participant 2 Monitor Hearing test 7

8 Results of pure tone audiometry Nonhandicapped people (31) 8

9 Results of Hearing Test Non-handicapped Person who have the same type of hearing loss as the elderly 32dB 27dB The same level 32dB Audibility Not perceived at over 55dB(A) 800Hz + 2kHz 2kHz 800Hz + 2kHz High-frequency deafness cannot hear 2kHz even with the volume of 55dB. 2 band bands in 1/3 octave band is essential. 2kHz 9

10 4.Validity Check for Audible Distance Examination: Relation between sounds with 2 band bands and O.A. Sounds: 2 band bands 200Hz+2kHz, 200Hz+5kHz, 800Hz+2kHz, 800Hz+5kHz Volume: 46dB, 52dB, 58dB in O.A. (Target value) Sounds are generated from a speaker fixed to EV. Measurement of audible distance in driving at the speed of 10km/h Place: Japan Automobile Research Institute (JARI), Shirosato Test Center(background noise; 25dB) Participants: 12 (Non-handicapped) extremely quiet 10

11 Speaker Setting Speaker attached to the tip of EV 11

12 Pass-by Noise Spectrum(AA-PP Max. Level) 200Hz-2kHz 20 NPRM 200Hz-5kHz NPRM k 1.25k 1.6k 2k 2.5k 3.15k 4k 5k 6.3k 8k 10k OA Sound Pressure Level (AA-PP) [db(a)] One thrid Octave band frequency [Hz] Hz-2kHz NPRM 800Hz-5kHz NPRM k 1.25k 1.6k 2k 2.5k 3.15k 4k 5k 6.3k 8k 10k OA Sound Pressure Level (AA-PP) [db(a)] k 1.25k 1.6k 2k 2.5k 3.15k 4k 5k 6.3k 8k 10k OA Sound Pressure Level (AA-PP) [db(a)] k 1.25k 1.6k 2k 2.5k 3.15k 4k 5k 6.3k 8k 10k OA Sound Pressure Level (AA-PP) [db(a)] One thrid Octave band frequency [Hz] 200Hz-2kHz 200Hz-5kHz One thrid Octave band frequency [Hz] One thrid Octave band frequency [Hz] 800Hz-2kHz 800Hz-5kHz 12

13 Audible Test Setting Propsed Specified Used Sound Pressure Level [db(a)] k 1.25k 1.6k 2k 2.5k 3.15k 4k 5k 6.3k 8k 10k One thrid Octave band frequency [Hz] OA NHTSA background noise emanates from two speakers. Adjust volume to 55dB around participants ear. Comparison of frequency characteristics between NHTSA background noise and background noise from speakers 13

14 Audible Test Setting Press switch when participants notice sounds. Measurement of audible distance. 14

15 Test Result (Average of Audible Distance) Average audible distance [m] y = x R= R 2 = Overall Sound Pressure Level [db(a)] Verified audible distances of sounds with 2 band bands are proportional to O.A. under condition of background noise referred NHTSA in NPRM (55dB) 15

16 Conclusion Japan suggestions for the sound requirements for AVAS: 1.At least 2 band bands in 1/3 octave band, 2.Audible distance should be proportional to O.A. Japan conducted verification tests. Japan verified 1. and 2. 16

17 Thank you very much for your attention 17